Heat-Kit System Modular Contraflow Masonry Heater Core Assembly Manual

Transcription

1 Revised January 11, 2011 Heat-Kit System Modular Contraflow Masonry Heater Core Assembly Manual HK-22no 22 Firebox RR 5 Shawville Québec J0X 2Y0 Voice Fax mheat@heatkit.com

2 Material List (in addition to core components) 230 Standard Firebricks 4.5 x9 x2.5 (2.5 dimension may vary. Important: The 4.5 and 9 dimensions are important) 25 Firebrick Splits 4.5 x9 x Common clay bricks (8 x4 nominal) 2 bags Mortar Mix (ie., premixed with sand, as opposed to Masonry Cement, which requires mason s sand) Assembling the Bottom End The bottom end of a contraflow heater is the most complicated part of the whole job. The two downdraft channels connect here, underneath the firebox. As well, the chimney connection and the cleanout openings for the particular installation need to be determined and located here. We ve removed as much of this complication as possible with the Heat-Kit system. The insulated base slab allows you to do a dry layout first and make sure that everything is located properly in relation to the chimney and the slab. As well, our thinwall refractory castings simplify the job of making the necessary cutouts with a portable masonry saw or a skilsaw. If you take a little extra time at this stage, particularly with the layout, you ll avoid problems later on. asy22no.doc printed 1/11/2011 Page 2 of 19

3 31-3/4 Figure 1. 2 Base channels sit dry on insulating base Position insulating base slab dry to determine layout for heater and chimney. Mark final position at corners with a pencil. Install insulating base slab level onto a mortar bed. Before setting base channels, determine the best place in your layout to locate the cleanouts. One is needed for each base channel. Mark clean out cuts on the base channels. Mark chimney connection on base channel. Figure 2. Connecting channel is started Right base channel not shown (for clarity) Build connecting channel, using refractory mortar. (If there is a rear chimney, leave opening and span with flat bar supplied (notch bricks to accept flat bars, thus allowing you to maintain thin joints)). Firebrick shiner is flush with outside of slab. Firebrick split shiner is set to form a 6-1/2 channel. (Note: shiner = brick set on edge) Cut appropriate holes for chimney connection and for clean outs. In this example, a right side chimney and front channel cleanouts are shown. Set base channels dry as shown. Bottom seam will be sealed later by mortar slush between channels and facing. asy22no.doc printed 1/11/2011 Page 3 of 19

4 Figure 3 Form connecting channel ceiling as shown. Sponge inside of channel to remove hanging drips. Fill any large gaps between bricks and lower channel with regular mortar. Figure 4 To form support for firebox floor, build up fill as shown to same height as firebrick. Arrow indicates approx. 8 channel for ashes. Install 14 flatbar as shown to provide extra support for firebox floor. Use mortar joint to gain height Corner Lead Install firebox floor onto generous mortar bed and level accurately. Back corners of floor line up with leads that are precast into lower channels. Ensure full mortar bed between flat bar and floor. You are now ready to build the firebox. Figure 5 asy22no.doc printed 1/11/2011 Page 4 of 19

5 View of assembly up to firebox floor level. Note that the fill bricks underneath the floor have been dry stacked in order to come out to the right height. Mortar is used to seal the head joints and the spaces between the bricks and the rear and side channels. The 2 steel flat bars are mortared, and there is a full mortar bed between the flat bars and the firebox floor. The two lower channel cutouts in this installation are connections for a heated bench. (Dec /08) Updated view of firebox floor, with hole for rear grate. Note that it overhangs the firebrick connecting tunnel, and the back of the hole is filled with mortar and angled to form a chute for the ashes. asy22no.doc printed 1/11/2011 Page 5 of 19

6 Setting Firebricks Firebricks are laid up with clay air setting refractory mortar ( Sairset, or fire cement) with thin joints. Only enough clay needs to be used to completely fill the joint. No joint thickness needs to be built up - you are only filling in gaps and irregularities between the bricks. Although masons are used to trowelling firebricks, the best joints are obtained by dipping the bricks into mortar that has been thinned to the right consistency. It looks messy, but the cleanup is easy later with a sponge. The Sairset that comes with the heater core kit is at trowelling consistency. For dipping, you will need to thin it with water. A drill powered drywall mud mixer works well for this. You can tell if the Sairset has the right consistency by floating a firebrick in it. It will sink about half way. We like to dip the bricks and also keep a margin trowel (small rectangular trowel) handy for the odd bit of trowelling. Assembling the Firebox The firebox is laid up from standard firebricks. Standard firebricks are 4 ½ wide by 9 long by 2 ¼ thick. The thickness will vary between 2 ¼ and 2 ½ depending on the supplier. Since the Heat-Kit is designed around the standard firebrick module, it is important to check the width and length of your bricks beforehand, to avoid having to make modifications to the assembly procedure. The firebox consists of two shells of firebricks set on edge. This allows the inner shell to be a field replaceable firebox liner. The firebrick installation sequence has been numbered. By following this order, you maximize the ability to bury odd lengths where they don t show and reduce the amount of precise cutting that you have to do. Note that full contact between inner and outer shell is not required at the inside corners. Where convenient, a little play right at the corner provides some expansion room for the liner. asy22no.doc printed 1/11/2011 Page 6 of 19

7 Figure 6 Lay out the firebox as indicated, using air setting refractory mortar. Line up back corners with the leads that are precast into the lower channels (right channel deleted from drawings for clarity). Outer width of firebox is 31 ½. Firebricks sit dry against base channels. The firebricks are numbered in the order in which they are installed. Figure 7 Exact bond is dependent on firebrick thickness, generally between 2-1/4 and 2-1/2. asy22no.doc printed 1/11/2011 Page 7 of 19

8 Completed outer shell. Note that hole in floor is not as shown in this photo. Figure 8 Figure 9 Top front firebricks are notched 1/4 x 4 for firebox lintel. Figure 10 Begin inner firebox. Note that the bricks are left about 1/4 short at the blind inside corners. The cut edges on these bricks are hidden. asy22no.doc printed 1/11/2011 Page 8 of 19

9 Figure 11 Figure 12 The inner firebox is set dry against the outer firebox. There is no mortar joint between the two fireboxes. asy22no.doc printed 1/11/2011 Page 9 of 19

10 Figure 14 Figure 13 Notch top course of liner as shown. Notches are 1/4 x 4 Firebrick floor slopes are glued in place with Sairset - this can be done later. Figure 15 asy22no.doc printed 1/11/2011 Page 10 of 19

11 Install firebox lintel. Brackets on lintel are for heat shields (firebrick splits, installed later, see Figure 35 Figure 16 Lay up next course as shown. Use a dry joint with lintel. Figure 17 If you have access to strapping tools, this course can be strapped as shown. This is optional. If a strap is used, then round outside corners of bricks slightly. The purpose of the strap is to transfer weight onto the outer firebox. This allows the complete inner firebox to be removed, if necessary, rather than in sections. Figure 18 asy22no.doc printed 1/11/2011 Page 11 of 19

12 Figure 19 A total of 16 soaps (8 bricks ripped lengthwise) is used. All bricks are either full length (9 ), ¾ length (6 ¾ ) or half length (4 ½ ). Figure 20 Next course. asy22no.doc printed 1/11/2011 Page 12 of 19

13 Figure 21 Set next course as shown. Seal gap between top of lower channels and firebox with silicone. Figure 23 Gas slot detail Figure 22 (Note: Ignore the bakeoven that is shown in the above illustration.) For easier heater startup during difficult conditions (cold heater, warm outside temperatures) we highly recommend installing a gas slot. This consists of a 2 X 2 direct connect. In the above example, the arrow shows the location for a right side chimney towards the back of the heater. Cut a notch in the channel at the appropriate location. Later, when facing the heater, create the direct connect to the flue liner by using firebricks or firebrick splits (see Figure 23 ) Install middle channels onto a bed of Sairset. Strap middle channels or use tie wire. When strapping, compress expansion joint gaskets no more than 50%. Strap at same level as firebox strap Clean off joints from inside. Make sure there is no mortar bridging at the expansion joints from inside. Install top channels and brace temporarily as shown. Plumb gasketed edges, which will then be corner leads for the remaining firebrick. asy22no.doc printed 1/11/2011 Page 13 of 19

14 Figure 24 Right channels removed for clarity. Without a bakeoven, a dummy mass is built up from firebricks as shown. This is required to soak up heat. Figure 25 Figure 26 Figure 27 4 courses with full bond. Leave an opening near the gas slot. At this point, check expansion joints. Make sure there is no mortar bridging at gasket rope, asy22no.doc printed 1/11/2011 Page 14 of 19

15 particularly inside channels. Figure 28 At this point, a height adjustment is necessary. Place a pencil mark 4-7/8 from the top on all 4 channel ears. Next, measure the height of 3 existing courses of firebrick. Using this distance, place a second mark on all 4 ears as shown. The second mark indicates the top of the next course. If an adjustment greater than 1-1/4 needs to be made, insert a course of splits. If the adjustment is less than 1/2, use ordinary brick mortar. For 1/2 to 1-1/4, use castable refractory or 1:1:5 portland:clay:sand mix. Alternatively, you can cut the bricks to height on a brick saw. If you have a brick saw, you can skip the height adjustment here and do it on the final course. asy22no.doc printed 1/11/2011 Page 15 of 19

16 Figure 29 Lay up the 4 courses of back and front infill. Make sure there is no mortar bridging at channel gaskets. Figure 30 Install ceiling transitions. They should be slightly higher than side channels asy22no.doc printed 1/11/2011 Page 16 of 19

17 Install ceiling slabs. Use a helper, and set up adequate staging (foot planks). Be careful handling them, as the insulating board on bottom is fragile. Using GE clear silicone, carefully seal all ceiling slab joints, particularly the shiplap joints and the bottom joint. If gap between slab and top of side channels is greater than 3/16, stuff with ceramic fiber first. Next, check firebricks for full joints. Next, check side channel gaskets and use silicone to seal where needed. Figure 31 asy22no.doc printed 1/11/2011 Page 17 of 19

18 Figure 32 Figure 33 (Note: ignore the bakeoven shown) Next comes a double wrap of fiberglass matt to act as an expansion and slip joint. The mat is somewhat fragile, and releases glass fibres if handled too much - wear old clothes. Two pieces of fiberglass are supplied -- a 38 wide piece and a 52 wide piece. Start with the 38 wide piece. Quickly dab silicone approximately 4-6 o.c. over entire area indicated. Start at top of ceiling slab and go 38 down. Carefully unfold fiberglass mat and, with a helper, wrap around heater. Make sure mat goes all the way to top of ceiling slab. Have helper hold in ends in place, and go around heater, patting the mat onto the silicone. Trim to give approx. 4 overlap, and secure end with metal tape supplied Second wrap of fiberglass mat is 52 wide, and also starts at top. Use same procedure as before. Trim around firebox and use offcuts to cover exposed firebricks at front. (Figure 34) asy22no.doc printed 1/11/2011 Page 18 of 19

19 Figure 34 Figure 35 Add two additional pieces as shown. Note location of firebrick split heat shields. If not installed already, set sloped floor pieces onto a bed of refractory mortar, similar to setting a firebrick. asy22no.doc printed 1/11/2011 Page 19 of 19